[clangd] Check getFunctionTypeLoc() for validity in InlayHintVisitor (#117296)

Fixes clangd/clangd#2223

Author: HighCommander4

clang-tools-extra/clangd/InlayHints.cpp

@@ -626,10 +626,15 @@ class InlayHintVisitor : public RecursiveASTVisitor<InlayHintVisitor> {
 
   bool VisitLambdaExpr(LambdaExpr *E) {
     FunctionDecl *D = E->getCallOperator();
-    if (!E->hasExplicitResultType())
-      addReturnTypeHint(D, E->hasExplicitParameters()
-                               ? D->getFunctionTypeLoc().getRParenLoc()
-                               : E->getIntroducerRange().getEnd());
+    if (!E->hasExplicitResultType()) {
+      SourceLocation TypeHintLoc;
+      if (!E->hasExplicitParameters())
+        TypeHintLoc = E->getIntroducerRange().getEnd();
+      else if (auto FTL = D->getFunctionTypeLoc())
+        TypeHintLoc = FTL.getRParenLoc();
+      if (TypeHintLoc.isValid())
+        addReturnTypeHint(D, TypeHintLoc);
+    }
     return true;
   }
 

clang-tools-extra/clangd/unittests/InlayHintTests.cpp

@@ -1576,6 +1576,22 @@ TEST(TypeHints, Aliased) {
   EXPECT_THAT(hintsOfKind(AST, InlayHintKind::Type), IsEmpty());
 }
 
+TEST(TypeHints, CallingConvention) {
+  // Check that we don't crash for lambdas without a FunctionTypeLoc
+  // https://github.com/clangd/clangd/issues/2223
+  std::string Code = R"cpp(
+    void test() {
+      []() __cdecl {};
+    }
+  )cpp";
+  TestTU TU = TestTU::withCode(Code);
+  TU.ExtraArgs.push_back("--target=x86_64-w64-mingw32");
+  TU.PredefineMacros = true; // for the __cdecl
+  auto AST = TU.build();
+
+  EXPECT_THAT(hintsOfKind(AST, InlayHintKind::Type), IsEmpty());
+}
+
 TEST(TypeHints, Decltype) {
   assertTypeHints(R"cpp(
     $a[[decltype(0)]] a;